1. Field of the Invention
The present invention relates generally to a conveyer system. More specifically, the present invention relates to a method and apparatus for mitigating the effects of the stretching and consequent twisting of a cable that is part of a cable conveyance system.
2. Background Art
Cables, due to their flexibility, have been used in conveyance systems for some time. The usual cable conveyance system 200 is shown in FIG. 2 and comprises an endless cable having disc members or buttons 210 attached thereto at even intervals and having a diameter slightly smaller than a conduit through which the cable and button assembly 200 is pulled.
In U.S. Pat. No. 4,195,725, which is hereby incorporated by reference, a drive unit for a cable conveyer is disclosed, having an improved design allowing the driving wheel to be disposed within the material being conveyed.
In U.S. Pat. No. 4,071,136, which is hereby incorporated by reference, a channel housing is disclosed to replace cable tensioning devices used in previous cable conveyor systems.
In U.S. Pat. No. 4,391,361, which is hereby incorporated by reference, an improved hold-down apparatus for cable conveyors is disclosed.
In each of these examples, and those cable conveyer systems 200 shown in FIG. 2, the wire rope, or cable 220, may stretch under tension. A consequence of stretching is a torque due to the twisted braid of the cable 220. No relief to this torque is provided in present cable conveyor systems 200 as the cable 220 is coupled to itself in a rigid arrangement with the couplers 110 shown. Hence, rotational stresses are unrelieved to the detriment of the cable 220 and other conveyor parts.
Therefore, there is a need for a reliable cable conveyor system providing an opportunity for a tensioned cable to twist. Additionally, a mechanism to permit the cable to retwist when relieved of tension is needed.